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Feeling Fatigued? Vitamin D Deficiency Might Be To Blame

Sometimes you're tired of feeling tired.


It’s normal to feel tired sometimes. Between running errands, making appointments, and keeping the house clean, simply living life can be exhausting. But there comes a point at which you’re too tired, and completing your everyday tasks becomes difficult. Does that sound like you? If so, you might be vitamin D deficient, which impacts your thyroid health and saps your energy. Read on to see if you need more vitamin D to cure your fatigue.

Vitamin D and Thyroid Health

Vitamin D shortfalls raise the risk of thyroid slowdowns, report researchers in BMC Endocrinology. “Vitamin D is essential for thyroid function,” says Richard L. Shames, MD, author of Thyroid Power (Buy from Amazon, $12.79) and creator of “It has to be present at sufficient levels for thyroid hormone to do its energizing work.” So when deficits occur (as they do in many women with a slow thyroid), fatigue often follows. Plus, new research links low D to Hashimoto’s, a top cause of thyroid slowdowns.

Adding to the problem: Because vitamin D is crucial for thyroid hormones to function efficiently, shortfalls can keep women who take thyroid medication from healing. Dr. Shames estimates that correcting low D levels has optimized thyroid treatment for more than half of his patients.

Quiz: Are you vitamin D deficient?

If you suffer from fatigue and two or more of the symptoms here, a thyroid-draining vitamin shortfall may be to blame.

  • Mental fog/forgetfulness
  • Sensitivity to cold
  • Weight gain
  • Anxiety or blue moods
  • Joint pain

What to Do if You Have a Vitamin D Deficiency

Get tested. Doctors can run blood tests to test vitamin D levels, and home tests are available at If your D level is less than 50 nanograms per decileter (ng/dL), the steps below can shore up stores to optimize thyroid function and restore energy.

Take a supplement. Supplementing with vitamin D is key, especially in the winter, when levels can dip due to less sunlight exposure. Dr. Shames advises taking up to 6,000 IU of D-3 if your levels are below 20 ng/DL, retesting after a few months and lowering your daily dose to 2,000 IU once levels reach 50 ng/dL. And opt for oil-based capsules. In a study at Atlanta’s Emory University, capsules lifted levels of the vitamin more than tablets.

Squeeze in some magnesium. Eating magnesium-rich foods like nuts, seeds, and leafy greens can help, says Dr. Shames. Indeed, research at Vanderbilt University in Nashville finds that magnesium activates enzymes that enhance the body’s ability to metabolize D.

A version of this article originally appeared in our print magazine, First For Women.

This content is not a substitute for professional medical advice or diagnosis. Always consult your physician before pursuing any treatment plan.

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